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1995 Lt1 Camaro cooling fans operate like this; Cooling fans (2 fans) come on 30 seconds after start up on high, stay on while driving, and turn off when brakes are applied. Stock car, no mods.

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  • Cars & Trucks Master
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Did you have it checked for DTC'S - diagnostic trouble codes ? The cooling fans are controlled by the PCM - engine computer , with the use of three relays ,located in the under hood electrical center . Do you know how to do electrical testing ?
Relay Driven Dual Cooling Fan Diagnostics Looking at wiring diagrams i don't see any connection between the brakes an cooling fans . Checking for DTC'S an doing electrical testing of control circuits from the PCM , Power circuits from the fuse / relay box . Checking grounds an pulling relays ,check for corrosion .

Electric Testing Techniques You Need to Know

View wiring diagrams here http://www.bbbind.com/free_tsb.html

ECM Inputs and Outputs Diagnosis

Posted on Mar 30, 2017

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Posted on Jan 02, 2017

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Where is the cooling fan switch located on my 2005 malibu 3.5liter v6


Cooling fan switch ? The cooling fans (2) on that motor are controlled by three relays . A coolant temp. sensor gives temp info to the PCM - engine computer .
During high speed operation the PCM supplies the ground path for the cooling fan 1 relay through the low speed cooling fan relay control circuit. After a 3 second delay, the PCM supplies a ground path for the cooling fan 2 relay and the cooling fan S/P relay through the high speed cooling fan relay control circuit. This energizes the cooling fan 2 relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the cooling fan S/P relay coil is energized closing the relay contacts and provides battery positive voltage from the cool fan 2 fuse on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have their own ground path. The result is a parallel circuit with both fans running at high speed.
The PCM commands Low Speed Fans on under the following conditions:
• Engine coolant temperature exceeds approximately 106°C (223°F).
• When A/C is requested and the ambient temperature is more than 50°C (122°F).
• A/C refrigerant pressure exceeds 1 310 kPa (190 psi).
• After the vehicle is shut off if the engine coolant temperature at key-off is more than 140°C (284°F) and system voltage is more than 12 volts. The fans will stay on for approximately 3 minutes.
The PCM commands High Speed Fans on under the following conditions:
• Engine coolant temperature reaches 110°C (230°F).
• A/C refrigerant pressure exceeds 1 655 kPa (240 psi).
• When certain DTCs set .
Watch this video ,it shows how it works !
Relay Driven Dual Cooling Fan Diagnostics

Nov 27, 2016 | 2005 Chevrolet Malibu

1 Answer

I have an 05rendezvous,need to locate switches for cooling system,fans aren't co ming on & now I'm going to need a new radiator,cuz plastic broke.But it broke before fans gave out.Which I changed stat


The engine cooling fan system is controlled by the body control module (BCM) and the powertrain control module (PCM) or engine control module (ECM). The BCM performs the calculations as to how long, when and what speed the cooling fans should turn on. The BCM then sends a class 2 message to the PCM/ECM to engage the cooling fan relays. If there is a malfunction with the BCM, the PCM/ECM will control the engine cooling fans independently. The engine cooling system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the PCM/ECM to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood accessory wiring junction block. The ground path is provided at G100.
During low speed operation, the PCM/ECM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the cooling fan 1 relay coil, closes the relay contacts, and supplies battery positive voltage from the cool fan 1 fuse through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the cooling fan 2 relay and the right cooling fan. The result is a series circuit with both fans running at low speed.
During high speed operation the PCM/ECM supplies the ground path for the cooling fan 1 relay through the low speed cooling fan relay control circuit. After a 3 second delay, the PCM/ECM supplies a ground path for the cooling fan 3 or S/P relay and the cooling fan 2 relay through the high speed cooling fan relay control circuit. This energizes the cooling fan 2 relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the cooling fan 2 relay coil is energized closing the relay contacts and provides battery positive voltage from the cool fan 2 fuse on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. The result is a parallel circuit with both fans running at high speed.
The BCM and PCM/ECM command Low Speed Fans on under the following conditions:
?€¢
Engine coolant temperature exceeds approximately 106?°C (223?°F).


?€¢
A/C refrigerant pressure exceeds 1 310 kPa (190 psi).


?€¢
After the vehicle is shut off if the engine coolant temperature at key-off is greater than 140?°C (284?°F) and system voltage is more than 12 volts. The fans will stay on for approximately 3 minutes.

The BCM and PCM/ECM command High Speed Fans on under the following conditions:
?€¢
Engine coolant temperature reaches 110?°C (230?°F).


?€¢
A/C refrigerant pressure exceeds 1 655 kPa (240 psi).


?€¢
When certain DTCs set.


The three relays are located in the under hood fuse / relay box ! You need to have it checked for DTC'S -diagnostic trouble codes ! An you need a GM Tech 2 scan tool !
This diagnostic procedure supports the following DTCs:
?€¢
DTC P0480 Cooling Fan 1 Relay Control Circuit


?€¢
DTC P0481 Cooling Fan 2 and 3 or S/P Relay Control Circuit


?€¢
DTC P0691 Cooling Fan 1 Relay Control Circuit Low Voltage


?€¢
DTC P0692 Cooling Fan 1 Relay Control Circuit High Voltage


?€¢
DTC P0693 Cooling Fan 2 and 3 or S/P Relay Control Circuit Low Voltage


?€¢
DTC P0694 Cooling Fan 2 and 3 or S/P Relay Control Circuit High Voltage


  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, command the Fans Low Speed ON and OFF.
Do the low speed engine cooling fans turn ON and OFF with each command?
Go to Step 3
Go to Step 4

3

Important:: A 3 second delay occurs before the powertrain control module (PCM)/engine control module (ECM) changes the cooling fan speed.
With a scan tool, command the Fans High Speed ON and OFF.
Do the high speed engine cooling fans turn ON and OFF with each command?

Aug 08, 2015 | Cars & Trucks

1 Answer

Where is the radiator fan switch located on a 2002 oldsmobile intrigue


The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the powertrain control module (PCM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood accessory wiring junction block. The ground path is provided at G113. The relays are located in the underhood fuse / relay box .
So ,what's the problem Paul , car overheating ? Fans not working ?
During low speed operation, the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the cooling fan 1 relay coil, closes the relay contacts, and supplies battery positive voltage from the cool fan 1 fuse through the cooling fan motor supply voltage circuit to the right cooling fan. The ground path for the right cooling fan is through the cooling fan 2 relay and the left cooling fan. The result is a series circuit with both fans running at low speed.
During high speed operation the PCM supplies the ground path for the cooling fan 1 relay through the low speed cooling fan relay control circuit. After a 3-second delay, the PCM supplies a ground path for the cooling fan 2 relay and the cooling fan 3 relay through the high speed cooling fan relay control circuit. This energizes the cooling fan 2 relay coil, closes the relay contacts, and provides a ground path for the right cooling fan. At the same time the cooling fan 3 relay coil is energized closing the relay contacts and provides battery positive voltage from the cool fan 2 fuse on the cooling fan motor supply voltage circuit to the left cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. The result is a parallel circuit with both fans running at high speed.
The PCM commands Low Speed Fans on under the following conditions:
?€¢
Engine coolant temperature exceeds approximately 106?°C (223?°F).


?€¢
When the A/C is requested and the ambient temperature is more than 50?°C (122?°F).


?€¢
A/C refrigerant pressure exceeds 1310 kPa (190 psi).


?€¢
After the vehicle is shut off if the engine coolant temperature at key-off is greater than 140?°C (284?°F) and system voltage is more than 12 volts. The fans will stay on for approximately 3 minutes.

The PCM commands High Speed Fans on under the following conditions:
?€¢
Engine coolant temperature reaches 110?°C (230?°F).


?€¢
A/C refrigerant pressure exceeds 1655 kPa (240 psi).


?€¢
When certain DTCs set.



So

May 11, 2015 | Oldsmobile Cars & Trucks

1 Answer

Why do radiator cooling fans start when key is put in on position


Under normal operation, in low speed, only the LH fan is initially in operation. Voltage is supplied to the low speed cooling fan relay through circuit 60 BK/LG wire. When the relay is energized, voltage fed to the LH cooling fan motor through circuit 538 GY/RD wire. Ground for the cooling fan is through circuit 57 BK wire. After the LH fan has been energized for 5 -10 seconds the RH fan will start automatically. Voltage is applied to the RH fan motor through circuit 3829 LB/BK wire. BK wire circuit 57 is also the ground.
Under normal operation in high speed both fans should operate from the high speed cooling fan getting a command voltage on circuit 30 BK/LG wire. The relay energizes both fans through circuit229 RD/OG wire while the low speed fan relays are de-energized.
The fans will come on immediately when the airconditioning compressor clutch is engaged mode and when the vehicle is in Drive. OBD-II trouble codes are P0480 low fan 1circuit, P0481 hi fan circuit & P0482 medium fan circuit.

Jul 14, 2014 | 2006 Ford Escape

1 Answer

1995 Camaro V6 3.4L Electrical Issues


Did you check the cooling fan relay's ? Your vehicle has three of them . Free wiring diagrams at http://www.bbbind.com/free_tsb.html Enter vehicle info. year , make , model an engine size . Under system click on engine , then under subsystem click on cooling fans . Then click the search button then the blue link . Learning how the fans work then testing the electrical circuits is how we as Technician solve problems like this . We don't ask if anyone has this issue an knows how to solve it . Someone else's fix maybe different from what it will take to fix yours .
The cooling fan's are computer controlled ,by the PCM - powertrain control module . When the engine coolant temp. gets hot enough the PCM see's this through the use of a coolant temp. sensor . When it reaches 212 degress the PCM energizes relay # 1 sending B+ voltage through both cooling fans to ground causing low speed .
Relay Driven Dual Cooling Fan Diagnostics

Aug 23, 2017 | 1995 Chevrolet Camaro

1 Answer

R&r 5.7 distripter in 1996 camaro


Replacing the Optispark Distributor is a real pain in this year and the LT1 engine.
Here are the steps
Remove accessory drive belt
Remove air intake hose to engine
Remove Radiator fans (unplug wiring harness first)
Drain the cooling system
Remove water pump (unplug water temp sensor first, tie hoses back out the way)
Remove Crankshaft balancer (you can get around the hub).
Remove Optispark cap and the rotor, the remove the bolts that hold the distributor to the block

Reverse to assemble.

Jul 21, 2011 | 1996 Chevrolet Camaro

1 Answer

I bought a 95 Camaro z28 with a lt1 v8 and I just changed alot of sensors and the water pump, pcv, thermostat, gauge sensor ,all the cooling hoses ,spark plugs and wires ,new opti-connector,fans are...


Did you burp the air out of the cooling system? That needs to be done if you haven't - air will trap the thermostat and keep it from opening. Check my tips and tricks for how to do this.

Jul 15, 2011 | 1995 Chevrolet Camaro

1 Answer

1989 camaro cooling fan failure, how do i fix it


When was the last time the thermostat was changed , the fans are only supposed to come on before the temp gets to high if the fans come on when you turn the air conditioner on then it is not the fan.

Sep 07, 2009 | 1989 Chevrolet Camaro

1 Answer

Car runs hot at an idle. turn on the air and the fan comes on and cools off . does the ect control the fan function when the air is off? 1994 camaro 3.4.


The Cooling fan is Wired in in such a way so as to Automaticly Turn on Cooling Fan If the A/C is Switched ON. If "WITHOUT the A/C on" The Cooling Fan Doen NOT come ON Untill Engine. is @ 210-230 Degrees
There IS a Problem with the Engine COOLING SYSTEM, A Faulty Coolant Temp Sensor Will Cause this Problem. The Cooling fan is Also A Candidate For Testing.

Answering your Quwstion YES The Engine Coolant Temperture Sensor Tells the ECM What the TEMP Is and the ECM Grounds the Cooling FAN Relay to Turn ON Cooling FAN. Temp Sensor is the Usual Culpret, BUT Relay Comes in a CLOSE Second. Hope this Helps !!!

Jun 15, 2009 | 1994 Chevrolet Camaro

1 Answer

Radiator electric cooling fan cycles on and off every few seconds


Had the same problem with a Neon same age as yours. Mine started after driving through a large snow storm that packed snow under the hood. Turned out there is a relay or sensor for the fan that had to be replaced. Once this was done the problem was fixed.

Nov 13, 2008 | 1995 Plymouth Neon

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